English French German Italian Spanish

Commando Fork Slider - Mirror Image of OEM Disc Slider Sought

Submitted by james_eastwood on Thu, 20/02/2025
Forums
Commando

I'm wondering if anyone out there in Commandoland knows where I can source an opposite handed disc-side slider from, for use as the 'other' fork leg, so that I can fit twin brake disks?

Norman White used to supply these as pairs, but since retiring hasn't any left.  I don't know who supplied the castings for him either?  It's a pity he didn't sell the design on - so have I missed the Bus?

I've seen photo's of other owners with this cute set-up, and know of at least one brave Pilgrim who had suitably dimensioned caliper brackets welded on to his other leg, but frankly, I don't reckon it's good engineering practice.

I'd also like to hear from anyone who has already gone down this same route, and of their experiences.

Jim

 

Submitted by julian_wells on Thu, 20/02/2025

Permalink

The very expensive alternative would be left- and right-hand PR sliders and associated discs (AN do disc carriers to suit the standard five-bolt hubs as well as for the six-hole PR hubs).

If you are really made of money (and if they are currently available) you could also buy the handed AP racing calipers.

Cash-rich I'm not!!

It's a MK3 850, and the forward facing "shell" caliper has never looked quite correct in this position.

I would like to put the caliper(s) behind the fork legs - a triumph of style over better heat dissipation I know!  

I could stay with a single disk, and simply swap the legs over, but one urban legend is that the factory originally swapped the sliders on the MK3 because of the new rear disk brake being on the right. Supposedly in the interest of "hands-off" stability, and I need as much stability as I can find.

So even a single disk set-up might benefit from using a mirrored slider.

But why stop there!  Avoid fork twisting and fit two - RGM now make those ine-piece smart billet twin disk hubs, and I have done some wheelbuilding.  I reckon it would look so right.

Submitted by ashley_cutler1 on Fri, 21/02/2025

Permalink

With a 13mm master cylinder, braided hose, standard caliper and a well bled system you should be able to get the pads to chew into the cast iron disc. Email me and I will send photos of the wear on mine. The trick is bleeding the system on the MK3.   

That's my default position Ashley, but twin disks would help avoid twisting of the forks. And look fiendishly neat?

It would also mean swapping the forks sliders over if I want the caliper at the rear of the slider, and being a MK3 I would prefer it to be on the left side, but if needs be....

I have good experience of operating a single front disk on my Guzzi (an integrated braking system that works well IMO) - its a question of getting the correct hydraulic ratios.

I'll see if I can send you my email address - if Alan E in Bristol can do this, so should I ??

Attachments
Front Master Cylinder Ratio Chart.jpeg

Yes I noticed that the mistake norton made was using the original caliper bleed holes with the top centre hole directly under the "D" where as the mk3 top centre is now under the "O", which puts the bleed holes in the two o-clock position.

My quick fix for this was to cut two grooves in brake pipe bracket so I can easily slide the Caliper & pipe up and forward to the correct angle for bleeding without removing anything else.

 

Attachments
20250324_134454.jpg

Submitted by mark_savage on Sat, 22/02/2025

Permalink

https://youtu.be/lxGEXfTE2Pk

There was quite an interesting YouTube video (shame about the background noise though) about the development of the Commando by Brian Slark and Mick Ofield and the reason given for placing the caliper in front of the slider was to stop water being directed into it when it rained. This gets a mention 55 minutes into the video. The reason it went to the left was to save producing a new slider I'd imagine.
 

Submitted by neill_watkins on Sun, 23/02/2025

Permalink

I've used modified O.E right side disc sliders on the left with my Atlas twin disc front end since 1981 and my Mk3 since 2007.
I compared single and twin discs on the Atlas in back to back rides on the same day. No fork twist, smooth controlled and stronger braking with the same Lockheed pads and standard Norton Lockheed master cylinder. 

No noticeable difference with the extra weight and went on to complete over 70k+ miles without problems. 45k+ so far on the Mk3.
The worst weather I've ever ridden in has been on these two bikes with callipers behind the forks and no probs with rain in the callipers, same on my Yamaha (114k miles)  More likely rain will be a problem with the calliper out front.

The whole process including modifying a Norton Lockheed calliper is way beyond the scope of the forum but Access did a short post on my bike in 2017.
https://www.accessnorton.com/NortonCommando/dual-disc-brakes-on-commando.10730/

DIY with original callipers you have to be pretty hard core, it's a lot of hard graft to get it all working right, properly aligned. and not so cheap these days. 
I met another UK Commando owner at the 2018 Austria rally with a nicely done conversion. Similar and using standard modified callipers but differing in minor details.

 

Submitted by james_eastwood on Mon, 24/02/2025

Permalink

Thanks Neil, that's good to know, and that's one of the very posts that got me toying with the idea in the first place - it looks so right, and the hydraulic ratio using the factory 16mm master cylinder is reasonable too, @ 30.8 : 1, so that should work OK.

The owner of that bike has made a great job of it all, and I love the obvious attention to detail, though personally I would have retained the factory stainless mudguard, plus a mudflap.  His name is also Neil, and I was rather hoping that he might chime in at some point?  Please PM me Neil!

I don't know that I'm particularly hard-core, and that will cause a few friends to chuckle, but the prospect of converting a caliper isn't so daunting - and I do have some skilled friends to call on.

I confess that I've also thought about fitting a complete twin Brembo Italian front end, a la Norton 96,  but that defeats the objective somehow?

As an OAP this is probably my last Commando refreshment, and a final attempt to develop the bike more to my liking - my own MK4 concept.  A better front brake is a must, and I fancy twin shell calipers, the missing next evolutionary step before the big disk conversions.  So the hunt continues...

Attachments
Neil'sTwinShellDiskBrake.jpg

Submitted by neill_watkins on Mon, 24/02/2025

Permalink

Hi James
yes that is my bike, further refined since then with Nissin floating discs and Smiths electric speedo and drive, titanium flanged bolts etc. Now lighter than the standard Mk3 front end, not strictly necessary but a satisfying project. Photo below
I never liked the clunky looking stainless mudguards even tho they were in perfect condition. Sold them a while back. 

The discs in the Access photo are Yamaha RD400. I bought 3 of them freshly ground and drilled at a Popham bike jumble along with the 36 spoke Yamaha hub for around £40.

In your case a better starting point would be the 40 spoke RGM hub with Girling stainless floating discs, much better than the heavier rust prone originals. I would fit one on the rear too and use Ferodo Platinum pads.
 
The twin disc hub has a symmetrical spoke base angle to centre the wheel between the forks rather than the awful offset standard arrangement 

I'll send you a message and further info if you decide to go ahead with this conversion. Where are you located?
 

Attachments
BEB15FAB-5BFE-4EC2-8E3D-9BA04A1DBB31.jpeg

Apologies I had visions of a shopping trolley!. No it's an 18" x 4.25" Morad for 160/60 18 radials. I made two custom swingarms to suit, the other's on the Atlas.
Front is an 18" x 3.50" Morad for 120/70 18 radials. Rims as recommended for the tyre sizes.
I've always used Central for wheel builds, great service over the years.

Mk3 hub with cush drive alloy spider and rubbers mated to a Kawasaki GPz500S sprocket carrier with 42t 520 JT sprocket. Various sizes available but with a 21t front this retains the stock 850 gearing, the best for me.

160/60 radial is 649mmø.  410 x 19 TT100 is 672mmø so -23mmø or -11.5mm ride height (-3.6%)

I fitted 18" Akronts on my Atlas in the 80s using TT100/K181. Front was WM4 2.50" with a WM5 3.00" rear. Needed massaging of the Featherbed swingarm to fit the tyre.
The difference was immediately noticeable, handling positive with a more planted feel for want of a better word.

 

Just guessing it's a 18 x 3.00 Akront. WM sizes give up around WM4 (2.50).

Anyway, do tell all about the rear wheel hub. Looks like it has replaceable sprockets. Have you engineered a sprocket carrier to fit the standard Mk3 hub and cush drive or is it a different hub altogether?
 

I seriously underestimated the size of that rim, not surprising you wondered what I was on about :)

I have previously made up a sprocket carrier from a block of aluminium to take TZ sprockets and bolted it to the Norton 5-point cush-drive paddle in the Mk3 hub. Not familiar with the setup on a GP500 but do I gather that you've cut off the drive paddles on the back of the Kawasaki sprocket carrier and bolted to the Norton paddle in a similar way?

I have seen something similar to my setup where the sprocket carrier was machined with projections on the back to engaged in the same way as the Norton sprocket casting but that was beyond my scope.

Yes I did it the same but no locking ring and the heavy steel backplate plate replaced with a carbon fibre copy.
I don't have the facilities to machine a large block of material, just my shed, hacksaw, files, swearing etc.. The AN cush rubbers are still perfect. Another great feature of the Mk3.

The Nissin discs were for TZ250/350 race bikes. Very light, strong braking and minimal wear with Ferodo Platinum pads. 

GPz500S the ideal sprocket carrier, cheap and a wide range of JT sprocket sizes will fit. Needed the thinnest and strongest DID 520ERV3 race chain to clear the tyre and primary case but works well. Change both sprockets and chain around 20k miles. 520ERV7 the latest version is used on 1000cc road & race bikes.
 

Attachments
5981AA2F-2469-4130-8467-84C136A4CF3A.jpeg

Well that looks fine to me, all in the photo quality and better than the O.E. cast steel one. Is that on your old race Commando or a Mk3?

Submitted by stan_thomas on Sat, 01/03/2025

Permalink

It's one of the variants used on my race Commando which was a mix of 850 Mk2 & Mk3 parts. Not strictly CRMC compliant but nobody complained :)
MK3 rear brake

Submitted by ashley_cutler1 on Mon, 24/02/2025

Permalink

I think the other twin disc set up that has been seen is off a Suzuki, I believe the conversion was done by New Zealand owner living in the UK. It uses the whole front front end of the suzuki. 

Submitted by alan_elstob on Mon, 24/02/2025

Permalink

James,

A good few years ago a chap in Bristol grafted the brembo twin disc front end from an old police rotary interpol onto his commando. Actually looked ok, notwithstanding the alloy and black paint on the fork legs were a tad corroded. It was also a relatively low budget exercise.

Cheers, Alan 

Submitted by james_eastwood on Mon, 24/02/2025

Permalink

Aha - you'll know the bike intimately then Neil!  I didn't appreciate that you were the one and the same.

Apologies also for using the Americanised  term "disk"rather than "disc" - I clearly spend to much time catching up on missed threads on the Access Forum on dark winter evenings.

I'm based in sunny Bradford, and usually spend 3-5 months each year at my rustic hovel in SW France, courtesy of an Irish Passport, so I do regularly go off the radar.  I travel down the M1, then Rugby, Banbury, skirt Oxford, and then down through Hampshire to Portsmouth and beyond.

Neil, your close-up photo  - now that's a thoroughly neat conversion, and I do like the scalloped bolt heads.  Handsome. (I'll defer discussing Smiths style speedo drive boxes with you to another time!). Your kind offer to advise is appreciated.

I notice the Maxton slider sticker, and assume that you have had work done and bespoke bushes made up to suit?  (BTW, did that include something similar to plastic Turcite bottom bushes?).  Is there a backstory?

Back to Norman White's castings - I bet there a few sitting on the shelves somewhere?  I also wonder who made them - it could well be wherever Andover Norton get their legs cast?  Does anyone know?

Norman did mention that he welded the lugs to a slider to create his pattern, and it does seem such a shame if that and the drawings are effectively lost, along with details of his suppliers. (This also applies to his unique front primary belt drive rubber cush pulley, slimmed down PR head steady, and the rest of his twin 10" disc brake design etc).  The likes of which, are most unlikely to ever become available again??

It's quite easy to convert the stock disc slider to left. Just blending work and removing the mudguard boss. 
Hardest part is lining up the calliper because the cast slider mount is slightly offset. Calliper must be central and parallel to the disc before and after welding the new lug on the opposite side. 

Wouldn't recommend fully welding a bracket to a slider but the Norton calliper is virtually immune from welding distortion. I gas welded the original Atlas calliper on a building site in Bermondsey 1981.

Pic below shows the original Atlas front end I'm currently rebuilding with it's reground Suzuki discs, speedo drive and hub from 1981. Now with a new rim and Maxton Roadholders.

I got both sets of Maxton forks and rear shocks done in 2005. The Atlas set had been sitting in the boys bedroom until now. You send the sliders, stanchions and bottom circlips, they fit Honda cartridge inserts, Turcite type bushes and special seals. Putoline 5w synthetic fork oil

Expensive but durable, firm and supple. I stripped the Commando set last year after 45k+miles.
No measurable signs of wear but rear shocks were rebuilt by them. Buy all the expensive bits while you're still working!

Attachments
8CF16E19-5227-4411-AEBA-B6116AF2DE4F.jpeg

Submitted by james_eastwood on Tue, 25/02/2025

Permalink

I'm impressed Neil, and food for thought. Thanks.

That means the twin hub, rim, and discs need to be built up first, and bolted into the forks to provide the datum points for tack-welding the new fork lug accurately.

For now, I'm going to hold out for sourcing a new cast-in-one mirrored slider while I'm pre-occupied sorting my gearbox out.

I appreciate that the seeming non-availability of this other slider doesn't prevent any Commando from being on the road, but given that Norman White has already done all the heavy lifting, is this not the sort of thing that the Spares Scheme might consider?  There are also his other items as well - particularly the unique front belt drive pulleys with an integral cush?

So I've suggested it via an email to NOC SparesAdmin.
 

Submitted by james_eastwood on Fri, 28/02/2025

Permalink

I guess the limiting factor once the brakes have been uprated is maintaining tyre adhesion, so that implies the best tyres and wider rims for a larger contact patch. But where to draw the line?

A twin 10.7" disc brake should prove more than adequate for me, upsizing a touch, using say an Avon 100/90-19 on a WM3 rim, and I can see the logic of why Norman's own design used 10" dia. discs.

I'll bet electric scooter owners don't have these kind of considerations to weigh up? Neither will they be searching for that elusive mirrored slider.

 

Attachments
electric scooters.jpg

 



© 2024 Norton Owners Club Website by 2Toucans